An essential nutrient is a nutrient required by an animal for optimal health and functioning that must be obtained from dietary sources due to the fact that the animal does not have a metabolic mechanism for synthesis of the nutrient in sufficient quantities to meet body requirements. For example, certain fatty acids, such as omega-3 fatty acids, are considered essential for humans since the human body does not possess the enzymes required to produce them in sufficient quantities. As such, they must be obtained from other dietary sources. Most often, such nutrients are found in certain food sources and are ingested.
Essential omega-3 fatty acids, such as alpha-linolenic acid (“ALA”), docosahexaenoic acid (“DHA”) and eicosapentaenoic acid (“EPA”) have been implicated in maintaining human cardiovascular and mental health. Particularly, DHA is found in the membranes of brain, retina and nerve tissue, where it is physiologically essential for function, as well as in heart and blood cells.
ALA is readily found in certain plant and vegetable sources, such as flax seed, leafy green vegetables and nuts, and is therefore not typically lacking in the diet of most individuals. ALA, even when abundant in the diet, is readily oxidized, potentially resulting in a less effective uptake of ALA by the body than would be expected based on dietary levels of ALA. As well, ALA has no known direct function in the body, aside from acting as a precursor molecule for other polyunsaturated omega-3 fatty acids, such as DHA and EPA (Sinclair and Attar-Bashi Lipids (2002) 37:1113-1123.)
Although ALA may be converted by the body to DHA or EPA, this conversion requires multiple metabolic steps and occurs at an extremely low efficiency in humans, dogs, cats and birds. For humans, one study indicates that the conversion of ALA to DHA in human adults may be as low as 3.8% on average, based on conversion of deuterated dietary ALA to DHA (E. A. Emken et al., Biochim Biophys Acta (1994) 1213:277-288). A further study in young adult males detected no conversion of ALA to DHA over a 21 day period (G. C. Burdge et al., Br J Nutr (2002) 88:355-363). As well, subjects fed diets high in ALA did not show an increase in DHA levels, including the levels of DHA in breast milk in lactating women (C. A. Francois et al., Am J Clin Nutr (2003) 77:226-233). As a consequence, the level of DHA/EPA produced in the body as the result of conversion of dietary ALA may not be sufficient to meet the body requirements.
DHA and EPA are found in marine plants such as algae and in fish, and are most abundant in oily fish. As such, a diet rich in fish or marine plants may provide required quantities of DHA and EPA. Many individuals, however, have diets that are not rich in these foods and therefore may not get an adequate supply of DHA and EPA.
Similarly, infants and young children, for whom proper brain development is critical, may not have an adequate supply of these essential fatty acids in their diet. Although infants that are breast-fed will obtain some ALA, DHA and EPA through breast milk, the levels of DHA in the breast milk is dependent on the mother's dietary intake of this nutrient. Infants fed formula will be dependent on the level DHA and/or EPA in the formula.
Clearly then, there is a need to provide alternate dietary sources of DHA and EPA.
To this end, U.S. Pat. No. 6,436,431 (Hoffpauer et al.) discloses a method of using rice bran as a carrier to produce an admixture that is fortified with various nutrients, including omega-3 fatty acids from fish oil. However, addition of an oily substance to a powder or granular mixture can cause clumping and may result in uneven distribution of the fatty acid throughout the admixture.
Similarly, food supplements and pharmaceutical products containing omega-3 fatty acids have been developed. For example U.S. Pat. No. 6,210,686 (Bell et al.) discloses a yeast fiber-based supplement that may be enriched with omega-3 fatty acids. The supplement may be taken alone or may be added to foods such as beverages, baked goods, puddings, confections, snack foods, or frozen confections or novelties. However, yeast fiber is not a food component normally found in many of these types of foods, and addition of the supplement may alter the taste or consistency of prepared foods.
EP Patent Application No. 0699437 (Bruzzese) discloses a pharmaceutical composition that includes EPA and DHA formulated into gelatin capsules. Gelatin capsules are not always a convenient method of ingesting these essential fatty acids, particularly for infants, children or for adults that do not like to take medicines or pills.
U.S. patent application No. 20020025983 (Horrobin) describes pharmaceutical supplements containing Vitamin K and an essential fatty acid, including EPA or DHA, or a food stuff that has been fortified with Vitamin K and the essential fatty acid. The fatty acid is derived from an oil containing the fatty acid, such as fish oil in the case of DHA and EPA. However, the teaching of this reference does not overcome difficulties associated with addition of an oily substance to foodstuff.
U.S. Pat. No. 5,962,062 (Carrie et al.) describes a formulated milk product that contains a given ratio of various fatty acids, including DHA and EPA, which are obtained from marine organisms. However, such products are not suitable for individuals with milk allergies or intolerances, or who prefer not to consume animal byproducts.
Therefore, there remains a need for alternate, easily consumable food sources that allow for the inclusion of an adequate supply of DHA and other essential fatty acids in adult, child and infant diets.